Two ways of grouping a dataset

ActiveRecord::QueryMethods#group

omit..

Array#group_by

It's useful when you want a hash such like

• key: the group id
• value: objects

You can get it by like this

Book.includes(:author).group_by{|book| book.author.name }

#=>
{
'Jhon' => [A, D, E],
'Alex' => [B, C]
}
# A,B,..E are Book objects.

Comments

[Ian bradbury]

Presumably you would also want an array and not an AR relation?